The invention concerns and electron beam vaporizer for vacuum coating systems with at least on crucible that receives a liner which holds the material to be evaporated.
With systems that are used particularly to coat optical substrates in a vacuum that have a gas-tight sealable, evacuatable working vacuum container (recipient) that can be provided with an atmosphere of inert gas, it is very important to precisely position the exchangeable liner holding the respective vaporizable material in the crucible to produce a high-quality coating.
The exchangeable liner holding the respective vaporizable material in the crucible cannot be precisely positioned according to the state of the art as shown in FIG. 1A-1E. The discernible undefined position between the relatively cold copper crucible 1 and the exchangeable, relatively hot liner 2 with the respective vaporizable material produces a highly fluctuating and uncontrolled temperature distribution in the liner.
The even vaporization and heat radiation is disadvantageous, and it produces inferior coats on the substrate to be coated. In addition, outgassing overflow material 3 (FIG. 1E) frequently arises that can change the position of the liner in the crucible during vaporization. High temperature fluctuations in the liner also produce thermomechanical stress that lowers the life of the liners due to wall cracks.
The problem of the present invention is therefore to precisely position the exchangeable liner holding the respective vaporization material in the crucible so that an even, high-quality coating is produced.
This is accomplished according to the invention by centering the liner in the crucible at a set distance from the crucible wall using spacers on the perimeter and possibly against the base.
These measures allow the liner to be clearly and repeatably positioned precisely which ensures even vaporization and heat radiation and hence a high-quality vaporization layer on the substrate to be coated. In addition, the specific distance between the liner and crucible permits the unrestricted and hence pressure-free outgassing of any overflow material.
Thermomechanical stress is also excluded which increases the life of such liners by several times.
In one possible embodiment according to the invention, the spacers are formed by bumps or ribs that extend from and are distributed over the outer wall of the liner or the inner wall of the crucible, or the spacer can be a surrounding projection, or the spacers can key into opposing grooves.